This invention relates to a surgical fastening apparatus which applies a plurality of fasteners simultaneously or substantially simultaneously and more particularly to such a surgical stapler provided with a lockout system for inhibiting activation of the stapler.
Cartridge type staplers are frequently employed in surgical procedures, such as for the stapling of a section of intestine or other body tissues. In a common form of cartridge, staples are arranged in an array of rows and columns. The array of staples, upon being dispensed to the body tissue, can close off the tissue, or other subject matter to be stapled, in a manner similar to stitching, but with a great saving of time. In these types of staplers, one jaw member comprises an anvil for bending the legs of the staples, and the other jaw member includes a cartridge containing the staples. Examples of such cartridge type surgical staplers are found, for example, in U.S. Pat. No. 4,568,009, U.S. Pat. No. 4,530,453, U.S. Pat. No. 4,508,253, U.S. Pat. No. 4,383,634, U.S. Pat. No. 4,354,628 and U.S. Pat. No. 3,494,533.
In the utilization of a surgical stapler having a U-shaped jaw configuration, correct practice requires that a lock pin be secured across the jaw members, so as to contain the body tissue between the jaw members before advancement or adjustment of the cartridge toward the anvil. The lock pin ensures among other things) that upon a compression of the body tissue by advancement of the cartridge towards the anvil, the tissue remains in the space between the two jaw members, namely, the anvil and the cartridge. Subsequently, after the gap between the anvil and the cartridge has been adjusted or closed to the required spacing, push bars within the cartridge are advanced by a suitable actuator mechanism of the stapler to urge the staples out of the cartridge, into the tissue, and against a corresponding set of channels in the anvil to bend the legs of the staples in response to advancement of the push bars. It is noted that throughout this procedure the lock pin is connected between the jaws.
A problem arises, however, that in the past it has been possible to operate these types of staplers without placement of the lock pin between the cartridge holding jaw member and the anvil jaw. Thus, there was the possibility that, in haste, a surgeon may fail to properly place the lock pin between the jaw members so that during clamping of the tissue or firing of the instrument the compression forces produced could displace some of the tissue from between the jaw members or cause the jaw members themselves to become misaligned resulting in improperly formed staples or incomplete stapling of the tissue.